The command iwconfig is a system administration commands (usually only for root). See man iwconfig. It is documented under section 8 of manpages. To know more about manpages see this post.

If you try in terminal,

$ type iwconfig 

iwconfig is hashed (/sbin/iwconfig)

and /sbin contains privileged executables. This is the reason why you are not able to have its full features when using as non-root user. There is nothing abnormal.

How to use sudo iwconfig without password ^[source]

You can use the NOPASSWD directive in your /etc/sudoers file.

If your user is called user and your host is called host you could add these lines to /etc/sudoers:

user host = (root) NOPASSWD: /sbin/iwconfig

This will allow the user user to run the command sudo iwconfig on host without entering a password. All other sudoed commands will still require a password.

It is recommended to use sudo visudo to edit the file. Read this nice post before you proceed. There you can find an alternative too if you do not wish to modify your /etc/sudoers

The other bad way [not recommended] is to ask sudo to read your password from a file where  your password is already stored. But this may be severe security concerns. -S switch enables sudo to read a password from standard input.

If you store your password in a file mypsd.txt that contains only your password followed by a new line character. Then the following command will run reading your password from that file,

cat /path/to/mypsd.txt | sudo -S iwconfig